[PATCH v2] mtd: m25p80: Make the name of mtd_info fixed

[PATCH v2] mtd: m25p80: Make the name of mtd_info fixed

[Hou Zhiqiang]

To give spi flash layout using "mtdparts=..." in cmdline, we must
give mtd_info a fixed name,because the cmdlinepart's parser will
match the name given in cmdline with the mtd_info.

Now, if use OF node, mtd_info's name will be spi->dev->name. It
consists of spi_master->bus_num, and the spi_master->bus_num maybe
dynamically fetched.
So, give the mtd_info a new fiexd name "name.cs", "name" is name of
spi_device_id and "cs" is chip-select in spi_dev.

Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
---
v2:
 - add check for return value of function kasprintf.
 - whether the spi_master->bus_num is dynamical is determined by spi
   controller driver, and it can't be check in this driver. So, we can
   not initial the mtd_info's name by distinguishing the spi_master
   bus_num dynamically-allocated or not.

 drivers/mtd/devices/m25p80.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index eb558e8..1f494d2 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -1011,8 +1011,12 @@ static int m25p_probe(struct spi_device *spi)
 
 	if (data && data->name)
 		flash->mtd.name = data->name;
-	else
-		flash->mtd.name = dev_name(&spi->dev);
+	else {
+		flash->mtd.name = kasprintf(GFP_KERNEL, "%s.%d",
+				id->name, spi->chip_select);
+		if (!flash->mtd.name)
+			return -ENOMEM;
+	}
 
 	flash->mtd.type = MTD_NORFLASH;
 	flash->mtd.writesize = 1;
-- 
1.8.4.1

Re: [PATCH v2] mtd: m25p80: Make the name of mtd_info fixed

[Brian Norris]

On Sun, Jan 26, 2014 at 02:16:43PM +0800, Hou Zhiqiang wrote:
> To give spi flash layout using "mtdparts=..." in cmdline, we must
> give mtd_info a fixed name,because the cmdlinepart's parser will
> match the name given in cmdline with the mtd_info.
> 
> Now, if use OF node, mtd_info's name will be spi->dev->name. It
> consists of spi_master->bus_num, and the spi_master->bus_num maybe
> dynamically fetched.
> So, give the mtd_info a new fiexd name "name.cs", "name" is name of
> spi_device_id and "cs" is chip-select in spi_dev.
> 
> Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
> ---
> v2:
>  - add check for return value of function kasprintf.
>  - whether the spi_master->bus_num is dynamical is determined by spi
>    controller driver, and it can't be check in this driver. So, we can
>    not initial the mtd_info's name by distinguishing the spi_master
>    bus_num dynamically-allocated or not.

How about spi->master->bus_num < 0 ?

>  drivers/mtd/devices/m25p80.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index eb558e8..1f494d2 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -1011,8 +1011,12 @@ static int m25p_probe(struct spi_device *spi)
>  
>  	if (data && data->name)
>  		flash->mtd.name = data->name;
> -	else
> -		flash->mtd.name = dev_name(&spi->dev);
> +	else {
> +		flash->mtd.name = kasprintf(GFP_KERNEL, "%s.%d",
> +				id->name, spi->chip_select);

I don't think this name is specific enough. What if there are more than
one SPI controller? Then there could be one chip with the same
chip-select. You probably still need to incorporate the SPI master
somehow, even if it's not by using the bus number directly (because it's
dynamic).

> +		if (!flash->mtd.name)
> +			return -ENOMEM;
> +	}
>  
>  	flash->mtd.type = MTD_NORFLASH;
>  	flash->mtd.writesize = 1;

Brian

RE: [PATCH v2] mtd: m25p80: Make the name of mtd_info fixed

[B48286]

Hi Brian,

> -----Original Message-----
> From: Brian Norris [mailto:computersforpeace@gmail.com]
> Sent: Tuesday, February 11, 2014 3:40 AM
> To: Hou Zhiqiang-B48286
> Cc: linux-mtd@lists.infradead.org; linuxppc-dev@ozlabs.org; Wood Scott-
> B07421; Hu Mingkai-B21284; linux-spi@vger.kernel.org
> Subject: Re: [PATCH v2] mtd: m25p80: Make the name of mtd_info fixed
>=20
> On Sun, Jan 26, 2014 at 02:16:43PM +0800, Hou Zhiqiang wrote:
> > To give spi flash layout using "mtdparts=3D..." in cmdline, we must giv=
e
> > mtd_info a fixed name,because the cmdlinepart's parser will match the
> > name given in cmdline with the mtd_info.
> >
> > Now, if use OF node, mtd_info's name will be spi->dev->name. It
> > consists of spi_master->bus_num, and the spi_master->bus_num maybe
> > dynamically fetched.
> > So, give the mtd_info a new fiexd name "name.cs", "name" is name of
> > spi_device_id and "cs" is chip-select in spi_dev.
> >
> > Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
> > ---
> > v2:
> >  - add check for return value of function kasprintf.
> >  - whether the spi_master->bus_num is dynamical is determined by spi
> >    controller driver, and it can't be check in this driver. So, we can
> >    not initial the mtd_info's name by distinguishing the spi_master
> >    bus_num dynamically-allocated or not.
>=20
> How about spi->master->bus_num < 0 ?
>=20
In spi slave driver, we can not see this case. The spi->master->bus_num=20
must be greater than 0, because before loading spi slave driver, the spi
controller driver will check spi->master->bus_num, if it is less than 0,
the spi controller driver will allocate a new bus_num dynamically. So it
is always greater than 0 in m25p80.c.

> >  drivers/mtd/devices/m25p80.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mtd/devices/m25p80.c
> > b/drivers/mtd/devices/m25p80.c index eb558e8..1f494d2 100644
> > --- a/drivers/mtd/devices/m25p80.c
> > +++ b/drivers/mtd/devices/m25p80.c
> > @@ -1011,8 +1011,12 @@ static int m25p_probe(struct spi_device *spi)
> >
> >  	if (data && data->name)
> >  		flash->mtd.name =3D data->name;
> > -	else
> > -		flash->mtd.name =3D dev_name(&spi->dev);
> > +	else {
> > +		flash->mtd.name =3D kasprintf(GFP_KERNEL, "%s.%d",
> > +				id->name, spi->chip_select);
>=20
> I don't think this name is specific enough. What if there are more than
> one SPI controller? Then there could be one chip with the same chip-
> select. You probably still need to incorporate the SPI master somehow,
> even if it's not by using the bus number directly (because it's dynamic).
>
Yeah, you're right. Actually the bus_num is used to distinguish different
spi controller. If the controller driver give a dynamically-allocated
bus_num, yourself should take the risk to use mtdparts in command line.
I think, it is spi controller driver's responsibility to assign a
reasonable bus_num to make sure using command line mtdparts riskless, then
it is unnecessary to change mtdinfo's name.
=20
> > +		if (!flash->mtd.name)
> > +			return -ENOMEM;
> > +	}
> >
> >  	flash->mtd.type =3D MTD_NORFLASH;
> >  	flash->mtd.writesize =3D 1;
>=20
> Brian
>=20

Zhiqiang Hou